1. Field of the Invention:
This invention relates to a heald frame for use in a narrow-width loom for weaving a continuous row of coupling elements in the form of a coiled synthetic resin filament into a woven fastener tape simultaneously with the weaving of the tape, and to a heald supported by the heald frame. More particularly this invention relates to a heald frame structure which is adequately tough and can achieve weight reduction, and to a heald structure which can be attached to and detached from the heald frame with ease.
2. Description of the Related Art:
In this kind of loom, a known conventional shedding device comprises a plurality of heald frames which are to be moved upwardly and downwardly by the same number of plate cams mounted on a common rotary shaft. Since the thickness of the individual cam plate has a lower limit in view of toughness, the length of the heald frame row cannot be smaller than a certain limit so that the difference in height of the sheds made respectively by the frontmost heald frame and the end heald frame would be large.
A shedding device which is free from such time difference in movement between the heald frames is disclosed in, for example, Japanese Utility Model Publication No. SHO 58-48383. In the shedding device, a pair of parallel rotary shafts extends under a row of heald frames, and as many plate cams as the heald frames are mounted alternately on the two rotary shafts, namely, plate cams half in number as the heald frames are supported by each rotary shaft. The individual plate cams are associated with respective cam followers which are arranged in a staggered pattern along the heald frame row for moving upwardly and downwardly in response to the movements of the plate cams. Without changing the thickness of the individual plate cams, the length of the row of the heald frames is reduced to about half the conventional length to minimize the difference in vertical movement between the front and end heald frames so that the degree of fatigue of the individual parts which move vertically is reduced, thus increasing the operating speed of the loom.
However, since all components of the conventional heald frame are made of steel, it would necessarily be that the total weight of the vertically moving parts including healds and heald frame attachments will be significantly large still in the present operating speed. More specifically, the total weight of the moving parts including the heald frames, healds, heald frame attachments and other associated members of the shedding device is about 2.1 kg, and the upper limit of operating speed of the loom for such weight is 1,500 rpm. If the loom is operated over the operating speed limit, influences due to the force of inertia of the individual moving parts would increase so that play would be created in the joints of the heald frames or the joints of the heald support rods and the heald frames would be broken or otherwise damaged, thus resulting in a non-stable continuous operation.